Field
This invention relates to methods of treating vertigo conditions by administration of an injectable pharmaceutical formulation comprising meclizine and a chemically modified cyclodextrin. This invention further relates to methods of treating nausea or vomiting conditions by administration of an injectable pharmaceutical formulation comprising meclizine and a chemically modified cyclodextrin.
Vertigo is a disabling disorder. The most common cause of vertigo is benign paroxysmal positional vertigo (BPPV). Vertigo may be a symptom of an underlying cause, such as in BPPV, or it may be suggestive of a more serious problem such as drug toxicities (e.g., gentamicin), strokes or tumors. Vertigo may be comorbid with skull fractures or brain trauma, sudden changes of blood pressure, or as a symptom of motion sickness. Vertigo may cause or include extreme dizziness, nausea, or vomiting episodes.
Nausea is a sensation of unease and discomfort in the stomach, usually accompanied by an urge to vomit. Nausea is medically not an illness; it is a symptom of several conditions, many of which may not be related to the stomach. Nausea may be indicative of an underlying condition elsewhere in the body. Motion sickness, which is due to confusion between perceived and actual movement, is an example. Nausea may result as an adverse effect of a drug. Nausea may be a problem during some chemotherapy regimens and following general anesthesia.
There are several types of anti-emetics, however, many pharmacological treatments, which are effective for nausea and vomiting in some medical conditions, may not be effective for other medical conditions. For example, metoclopramide and prochlorperazine, although widely used as anti-emetics, are ineffective for motion-sickness prevention and treatment.
Once vomiting has commenced, oral anti-emetic treatments become substantially ineffective. This may be because the orally administered drug may not be retained for a sufficient period of time to allow absorption from the stomach. Oral anti-emetic drugs may require up to 45-90 minutes for achieving their clinical effect and are thus not effective in treating expected vomiting episodes. In order for oral treatment regimes to be effective, the regimes would necessarily need to be ingested 1-2 hours prior to the expected vomiting episode. The net result is longer ER visits and often hospital admissions for patients with nausea-related conditions. Moreover, this limitation of oral anti-emetics makes them unsuitable for administration to post-anesthetized or unconscious subjects.
Intravenous anti-emetics are few in number, for example, cyclizine, may currently offer an alternative to oral anti-emetic therapies for the treatment and prevention of nausea and vomiting, however, it presents with a very short duration of action (1-2 hours). Such short duration of action limits the clinical application of cyclizine.
Meclizine is commercially available as an oral and as a chewable tablet. It is used in the treatment and prevention of nausea and vertigo associated with Mèniére's syndrome and in the treatment and prevention of motion sickness. It has also been used for the symptomatic treatment relief of hypersensitivity reactions and in pruritic skin disorders. See Martindale 30, 941. It is usually given in divided daily doses of 25-50 mg, with divided daily doses of up to 100 mg being used to treat severe vertigo and labyrinth disorders. Both meclizine base and meclizine HCl have been administered by the rectal route in similar doses to those administered by mouth. There are, however, no marketed meclizine rectal preparations. See Martindale 30, 941. There are also currently no marketed hypodermically administrable meclizine HCl formulations available. This may be attributed primarily to the poor aqueous solubility of meclizine HCl. Meclizine is virtually water insoluble, with meclizine HCl presenting with a water solubility of 0.1 g/100 ml. Merck Index, 12th Ed, 984. In particular, meclizine exhibits very low solubility at pH values greater than 2.0. Such pH values are desirable for reasons of injection comfort. Meclizine's anti-emetic duration of action may last up to 24 hours.
Thus, there is a need to provide stable, non-colloidal, injectable anti-emetic therapeutic formulations with longer duration of action, such as 12-24 hours. There is a need to provide otherwise insoluble and/or unstable anti-emetics, such as meclizine, as injectable therapeutic formulations for the treatment and prevention of nausea and vertigo. There is also a need to provide a viable hypodermic formulation for the treatment of nausea and vomiting as a clinically effective alternative to oral dosage forms.